Mike Battaglia, who sets the Kentucky Derby Presented by Yum! Brands morning-line odds, is struggling to decide between stablemates Dortmund and American Pharoah when it comes to choosing a favorite for this year's classic.

Trainer Rick Dutrow Jr. sent Big Brown for an easy work over the Churchill Downs surface May 1, and the imposing colt looked every bit the Derby favorite as he took to the track under regular exercise rider Michelle Nevin. Big Brown, installed as the 3-1 morning line choice following the April 30 post position draw, went three-eighths in :35 2/5.